1. Field of the Invention
The present invention relates to a method of recording information on a record medium having a data record region for recording data of files in a plurality of clusters and a file management information record region for recording file management information for managing the files recorded on the record medium.
2. Related Art Statement
Nowadays there have been developed various kinds of information record mediums for use in information recording and reproducing apparatuses. However, existing operating systems (OS) have been designed such that the record mediums such as magnetic disk which were existent at the time of designing the operating system are treated. Therefore, the existing operation systems are not effectively used for newly developed record mediums.
For instance, the opto-magnetic disk and high record density magnetic disk which have been developed recently have a very large record capacity such as several hundreds megabytes (MB). Contrary to this, the ordinary magnetic disk has a record capacity of only several tens of megabytes. Therefore, when the optomagnetic disk or high record density magnetic disk is used as the information record medium, the data record capacity is materially increased. Then, it is difficult or impossible to manage directly a large amount of data under the control of the existing OS which has been developed for treating the ordinary magnetic disk. In order to avoid such a drawback, it has been proposed to divide a large amount of data area into a plurality of blocks each having a data amount which corresponds to that of the ordinary magnetic disk. Then, the OS can treats the opto-magnetic disk or high record density magnetic disk by assuming that a plurality of ordinary magnetic disks are provided. In this manner, the newly developed record mediums can be utilized by slightly changing the existing OS.
In general, in case of using the record medium which could not be directly treated by the existing OS, one might consider to provide a working record region and to change a basic portion of the existing OS. However, in practice, an operation for changing the basic portion of the existing OS is very difficult even for an experienced person who is not a designer of the relevant OS. Therefore, as stated above, the basic portion of the OS is not changed, but a control program for a particular record medium is prepared, and this control program is patched on the OS. This control program may be easily prepared by the user for a newly developed record medium, because the basic portion of the OS is not changed. In this manner, the single OS may be utilized for treating various record mediums.
In almost all operating systems, the record medium is treated such that one or more sectors are treated as a single cluster which constitutes a minimum data unit, and files having various lengths are formed by using one or more clusters. In case of recording a plurality of files on the record medium, these files are successively recorded from the first record region toward the last record region. Once a file is recorded on the record medium, a title of file (file name) can be altered, a record position can be changed and the file can be erased. Once a file is erased, a new file may be recorded at a position in which said erased file was recorded. That is to say, the data can be rewritten.
When the files are recorded and erased in the manner explained above, the files are no more recorded successively on the record medium. In other words, the data could not be recorded in successive clusters continuously, so that it is necessary to store file management information representing positions of all the clusters. In practice, an address of a cluster is denoted by one or two bytes, and a table of all addresses of clusters in which the data are recorded has to be recorded on the record medium. By using such an address table, it is possible to manage the cluster chain information and cluster utility information for managing the files. By utilizing such an address table, it is allowed that the data can be recorded at arbitrary positions on the record medium, and thus the operation for recording new files and erasing old files can be carried out at will. The above mentioned address table is called the cluster chain management information.
Recently there have been proposed new types of write-once type record media such as optical disks and optical cards on which the data can be recorded with a very high density. However, the existing operating systems could not treat these newly developed record mediums. In the write-once type optical record medium, once recorded data could not be rewritten and the recording is carried out as a unit of a sector regardless of the length of data. In case of preparing a control program for such optical record mediums, the record mediums have to be assumed to be rewritable. However, in practice, the optical record medium such as the optical disk and optical card could not rewrite the data. Therefore, the cluster chain management information could not be rewritten, and thus there is a problem that a larger part of the record region is used to record the file managing information including the cluster chain management information.
For instance, when a file name is to be changed in the write-once type record medium in which the recorded data could not be erased, it is necessary to record a new file name in a new file management information record area, and even when a file is erased, the record area on which the relevant file has been recorded could not be utilized to record a new file, but the cluster chain management information has to be recorded. That is to say, since the cluster chain management information is changed frequently, a substantial part of the record region is occupied by the cluster chain management information. In this connection, it should be noted that one item of cluster chain management information is recorded in a single sector even if this information has a small length such as one or two bytes. In this manner, when the file is rewritten frequently, the record region on the record medium is used for recording the file management information.
Furthermore, when the cluster chain management information for denoting a series of clusters constituting a file is recorded on the record medium, it is also necessary to prepare a special record area for recording information representing that the cluster chain management information is changed. Apparently this further reduces the effective data record area. Moreover, a finite time is required for recording the cluster chain management information on the record medium, so that the recording operation is prolonged by that time. This might be a problem when the speed for recording the data on the record medium is low.